Typically, flat panel displays (“FPDs”) are made from two substrates with an intervening display medium and peripheral seal therebetween. Typically, the seal is created by depositing a liquid sealant material with an appropriate viscosity to the inner surface of one of the substrates about its periphery, or otherwise as necessary, to maintain the proximity of the substrates and the gap between the substrates once the substrates are applied together, to contain the display medium between the substrates, and to seal the edges to prevent contamination.
In the case of a liquid crystal display (“LCD”), the sealant is placed along all four edges on the inner surface of the substrate offset slightly in from the outer edges and typically having a width of a few tenths of an inch (several millimeters), “width” referring to the dimension of the sealant as viewed from the front of the display. Sufficient liquid crystal (“LC”) material is deposited into the space between the seal line to fill the entire region bounded by the seal line. The second substrate then is aligned and affixed on the first substrate to create a “cell.” The display assembly is cured by methods known to those skilled in the art, e.g., using ultraviolet light and/or heat.
Alternatively, the substrates may be affixed together without the display medium, and the display medium may be injected into the resulting cavity between the substrates through a port in the sealant after the cell is assembled. The port is then sealed to complete the peripheral seal of the cell. In a further alternative, the cell may be filled by the “One Drop Method,” as is known in the industry.
The peripheral seal resulting from these methods may extend into the space between the substrates several millimeters from the edges. Thus, the “active area” of the display, i.e., the area of the display in which information may be displayed to a user, has to be offset inwardly from the outer edges of the substrates by at least the width of the peripheral seal.
If two or more displays are placed against one another, i.e., “tiled,” to provide a larger effective display area for displaying information, the inactive areas due to the peripheral seals will create a dark or blank band between the active areas of the displays, which may detract from the overall images provided on the tiled displays. For example, the inactive area between two tiled displays will have a width at least equivalent to the sum of the width of the both seals along the contacting edges, e.g., several millimeters. This inactive area is sometimes referred to as a “mullion.”
It has been suggested that a pre-manufactured display, e.g., a liquid crystal display, may be reduced in size by cutting the display at a desired location to create an exposed edge adjacent a desired active area to be preserved, and sealing the resulting exposed edge of the preserved portion. Exemplary methods for resizing LCDs are described in U.S. Pat. Nos. 6,204,906, 7,780,492, and 7,938,051, which name the same inventor as the inventor of the present application. The entire disclosure of these references are expressly incorporated by reference herein.
The seal resulting from these methods may extend into the space between the plates from a few to several millimeters from the cut edge. Thus, the original active area of the resized display along the resealed edge occupied by sealant will be inactive and no longer capable of presenting an image. If two such displays are placed against one another, i.e., tiled as described above, to provide a larger effective display area, the resulting inactive areas may create a substantial inactive band or mullion between the active areas of the tiled displays.
Alternatively, U.S. Pat. No. 7,002,660 to Watson (the entire disclosure of which is expressly incorporated by reference herein) discloses a method for sealing the cut edge of a display by applying an external bead of flowable sealant material. Such a bead, however, may have an uneven cross-section and may have a height from a few to several millimeters. Thus, again if two or more of resized displays including such external beads are tiled together, the beads of the resealed edges may abut one another, resulting in a mullion that may also be several millimeters wide, which may reduce the overall effect of the effective display area of the tiled displays.
If the external bead is ground down or otherwise treated to reduce its height or profile, there is a risk that the seal may be damaged or compromised, which may allow display medium to leak from between the substrates contaminants to leak into the display.